Electron beam welding of large vacuum chamber body having a high emissivity coating

ABSTRACT

Embodiments disclosed herein relate to a large vacuum chamber body that has been welded together. The chamber body may have a high emissivity coating on at least one surface therein. Due to the large size of the chamber body, the chamber body may be formed by welding several pieces together rather than forging the body from a single piece of metal. The pieces may be welded together at a location spaced from the corner of the body, which may be under the greatest stress during evacuation, to ensure that the weld, which may be the weakest point in the body, does not fail. At least one surface of the chamber body may be coated with a high emissivity coating to aid in heat transfer from incoming, heated substrates. The high emissivity coating may increase substrate throughput by lowering the time that may be needed to reduce the substrate temperature.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Patent ApplicationSer. No. 61/114,871, filed Nov. 14, 2008, which is herein incorporatedby reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments disclosed herein generally relate to a large vacuum chamberbody that has a high emissivity coating to increase heat transfer fromthe incoming substrate and to a large area vacuum chamber body that iselectron beam welded together.

2. Description of the Related Art

To introduce a substrate to a vacuum environment from atmosphere, asubstrate may pas through a load lock chamber. To prevent radicalpressure changes, it may be beneficial to have the load lock chambervented to atmosphere when the substrate is inserted into the load lockchamber from outside the processing system and evacuated after thesubstrate is placed therein. Substrates that may pass through a loadlock chamber before being processed include semiconductor wafers, flatpanel display substrates, solar panel substrates and organic lightemitting display substrates.

Substrate throughput is always a concern. Industry has always looked forways to increase substrate throughput and lessen facility downtime. Thefaster that a substrate can be processed, the more substrates that canbe processed per hour. The processes performed on the substrates affectthe substrate throughput, but what occurs between processing alsoaffects substrate throughput. For example, the amount of time that ittakes for the substrate to be placed into a chamber affects thesubstrate throughput. Thus, even the load lock chamber affects substratethroughput because the load lock chamber, as mentioned above, may bemaintained in a vacuum state to prevent radical pressure changes.However, the load lock chamber also may interface with atmosphere whenthe substrates are placed into the load lock chamber. Thus, the loadlock chamber may change from a vacuum state to a vented state whichtakes time. Therefore, the load lock chamber affects substratethroughput.

Therefore, there is a need in the art for a load lock chamber capable ofincreasing substrate throughput.

SUMMARY OF THE INVENTION

Embodiments disclosed herein relate to a large vacuum chamber body thathas been welded together. The chamber body may have a high emissivitycoating on at least one surface therein. Due to the large size of thechamber body, the chamber body may be formed by welding several piecestogether rather than forging the body from a single piece of metal. Thepieces may be welded together at a location spaced from the corner ofthe body, which may be under the greatest stress during evacuation, toensure that the weld, which may be the weakest point in the body, doesnot fail. At least one surface of the chamber body may be coated with ahigh emissivity coating to aid in heat transfer from incoming, heatedsubstrates. The high emissivity coating may increase substratethroughput by lowering the time that may be needed to reduce thesubstrate temperature.

In one embodiment, a load lock chamber body is disclosed. The chamberbody comprises a plurality of pieces coupled together to collectivelyform the chamber body having an inside surface with four corners. Thechamber body additionally comprises a first piece, a second piece, athird piece and a fourth piece. The first piece comprises a firstportion having a first length greater than a first width and a firstopening extending therethrough and a first flange extending a firstdistance from the first portion in a direction substantiallyperpendicular to the first width. The first flange extends from a firstcorner of the four corners. The first piece also includes a secondflange extending a second distance from the first portion in a directionsubstantially perpendicular to the first width. The second flangeextends from a second corner of the four corners. The second piece iscoupled to the first flange and extends in a direction substantiallyperpendicular to the first width. The third piece is coupled to thesecond flange and extends in a direction substantially perpendicular tothe first width and parallel to the second piece. The fourth piece iscoupled to the second piece and the third piece. The fourth piececomprises a second portion a second length greater than a second widthand a second opening extending therethrough and a third flange extendinga third distance from the second portion in a direction substantiallyperpendicular to the second width. The fourth piece also includes afourth flange extending a fourth distance from the second portion in adirection substantially perpendicular to the second width.

In another embodiment, method of fabricating a load lock chamber bodyhaving an outside surface and an interior surface having a plurality ofcorners is disclosed. The method comprises positioning a first pieceadjacent a second piece and spaced apart by a gap, radiating an electronbeam into the gap and welding the second piece to the first flange. Thefirst piece comprises a first portion having first length and a firstwidth that is less than the first length. The first piece also comprisesa first flange extending a first distance from the first portion in adirection substantially perpendicular to the first width such that thefirst flange and the first portion meet at a first corner of theplurality corners. The first flange is spaced from the second piece by agap.

In another embodiment, a load lock chamber is disclosed. The chamberincludes a top plate, a bottom plate disposed opposite the top plate anda first side plate coupled to the top plate and the bottom plate. Thechamber also includes a second side plate coupled to the top plate andthe bottom plate and disposed opposite to the first side plate. Thechamber also includes a first slit valve plate coupled to the top plate,the bottom plate, the first side plate and the second side plate andhaving an opening therethrough. The chamber also includes a second slitvalve plate coupled to the top plate, the bottom plate, the first sideplate and the second side plate. The second slit valve plate is disposedopposite the first slit valve plate and has an opening therethrough. Thetop plate, the bottom plate, the first and second side plates, and thefirst and second slit valve plates collectively enclose a chambervolume. The chamber also includes a coating disposed on at least one ofthe top plate and bottom plate. The coating has a first emissivity thatis greater than 0.19 measured at 599 degrees Celsius.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a cross sectional view of a triple slot load lock chamber 100according to one embodiment of the invention.

FIG. 2 is an exploded isometric view of a load lock chamber according toone embodiment.

FIG. 3A is an isometric view of a load lock chamber sidewalls coupledtogether.

FIG. 3B is a top view of FIG. 3A.

FIG. 4 is an isometric view of the bonding location for a load lockchamber according to one embodiment.

FIG. 5A is an isometric view of two pieces to be welded together to forma portion of the load lock chamber body.

FIG. 5B is an isometric view of FIG. 5A after the two pieces have beenwelded together.

FIG. 5C is an isometric view of FIG. 5B from a different angle.

FIG. 6 is a schematic top view of a coated chamber surface according toone embodiment.

FIG. 7 is an isometric view of a coated chamber surface according toanother embodiment.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements disclosed in oneembodiment may be beneficially utilized on other embodiments withoutspecific recitation.

DETAILED DESCRIPTION

Embodiments disclosed herein relate to a large vacuum chamber body thathas been welded together. The chamber body may have a high emissivitycoating on at least one surface therein. Due to the large size of thechamber body, the chamber body may be formed by welding several piecestogether rather than forging the body from a single piece of metal. Thepieces may be welded together at a location spaced from the corner ofthe body, which may be under the greatest stress during evacuation, toensure that the weld, which may be the weakest point in the body, doesnot fail. At least one surface of the chamber body may be coated with ahigh emissivity coating to aid in heat transfer from incoming, heatedsubstrates. The high emissivity coating may increase substratethroughput by lowering the time that may be needed to reduce thesubstrate temperature.

The embodiments will be described below in regards to a triple slot loadlock chamber available from AKT America, Inc., a subsidiary of AppliedMaterials, Inc., Santa Clara, Calif. While the invention will bedescribed below in regards to a triple slot load lock chamber, it is tobe understood that the invention may be practiced in other vacuumchambers including those produced by other manufacturers.

FIG. 1 is a cross sectional view of a triple slot load lock chamber 100according to one embodiment. The load lock chamber 100 comprises achamber body 102 that encloses three separate chamber volumes 104, 106,108. The chamber volumes 104, 106, 108 may be electrically isolated fromone another and be atmospherically isolated from each other.

One chamber volume 104 may have a slit valve door 118 that opens andcloses to permit substrates 112 to enter and exit the chamber volume 104on the atmosphere side 140. Another slit valve door 120 may open andclose to permit a substrate 112 to enter and exit the chamber volume 104on the vacuum side 138. In the embodiment shown in FIG. 1, a robot endeffector 114 is shown inside the chamber volume 104 from the vacuum side138 with the slit valve door 120 open. Because the chamber volume 104 isopen to the vacuum side 138, the chamber volume 104 is under vacuum.

Because the chamber volume 104 is under vacuum, the upper wall 130 ofthe chamber volume 104 may deflect into the chamber volume 104 and awayfrom its normal position indicated by horizontal line “A”. Similarly,the bottom wall 132 of the chamber volume 104 may also deflect into thechamber volume 104 and away from its normal position indicated byhorizontal line “B”. The lift pins 110 are shown in their normalposition (i.e., extending from a horizontal bottom surface of thechamber volume 104), however, it is to be understood that the lift pins110 may deflect with the bottom wall 132 as well.

Another chamber volume 108 may have a slit valve door 126 that opens andcloses to permit substrates 112 to enter and exit the chamber volume 108from the atmospheric side 140. Another slit valve door 128 may open andclose to permit a substrate 112 to enter and exit the chamber volume 108from the vacuum side 138. In the embodiment shown in FIG. 1, the chambervolume 108 is sealed from the atmospheric side 140 and the vacuum side138 by the slit valve doors 126, 128 which are closed. Thus, the chambervolume 108 may be pumped down to an appropriate vacuum level. In sodoing, the chamber walls 134, 136 may deflect into the processing volume108 and away from their normal position as shown by horizontal lines “C”and “D”. The lift pins 110 are shown in their normal position (i.e.,extending from a horizontal bottom surface of the chamber volume 104),however, it is to be understood that the lift pins 110 may deflect withthe bottom wall 136 as well.

Another chamber volume 106 may have a slit valve door 122 that opens andcloses to permit substrates 112 to enter and exit the chamber volume 106from the atmospheric side 140. The slit valve door 122 is shown openwith a robot end effector 116 extending into the chamber volume 106.Because the slit valve door 122 is open on the atmosphere side 140, thechamber volume 106 may be at atmospheric pressure. Another slit valvedoor 124 may open and close to permit a substrate 112 to enter and exitthe chamber volume 104 on the vacuum side 138. Due to the evacuatedconditions in chamber volumes 104, 108, the walls 132, 134 of thechamber volume 106 may be deflected away from the chamber volume 106.

When the chamber walls 130, 132, 134, 136 deflect relative to theirnormal position, the walls 142, 144, 146, 148, 150, 152 to which theslit valve doors 118, 120, 122, 124, 126, 128 seal may also moverelative to their normal position. By moving the slit valve doors 118,120, 122, 124, 126, 128 with the chamber walls 142, 144, 146, 148, 150,152 when they move, the amount of rubbing between the slit valve doors118, 120, 122, 124, 126, 128 and the chamber walls 142, 144, 146, 148,150, 152 may be reduced and thus, particle generation may be reduced.

FIG. 2 is an exploded isometric view of a load lock chamber 200according to one embodiment. The load lock chamber 200 may be quitelarge. In one embodiment, the load lock chamber may be sized to receivea substrate having a surface area of about 8 square meters or more. Itis to be understood that the embodiments discussed herein may beapplicable to chambers sized to receive a substrate having a surfacearea of less than about 8 square meters. Due to the large size, forgingthe load lock chamber 200 from an ingot may be difficult. Therefore, theload lock chamber 200 may be fabricated from several pieces weldedtogether.

The load lock chamber 200 includes a top plate 202, a bottom plate 204,and a middle section 206. The middle section 206 may include two slitvalve plates/end pieces 208, 210 that each may have an opening 212therethrough to permit a substrate to enter and exit the load lockchamber 200. The end pieces may be connected by side pieces 216, 218.The side pieces 216, 218 may be coupled to the slit valve plates/endpieces 208, 210 by a weld 214.

FIG. 3A is an isometric view of a load lock chamber sidewalls coupledtogether. FIG. 3B is a top view of FIG. 3A. The load lock chamber has abody 300 with slit valve plates/end pieces 302, 304 each having anopening 306, 308 sized to permit a substrate to enter and exit theprocessing area enclosed by the body 300. Side pieces 310, 312 arewelded to the slit valve plates/end pieces 302, 304 by welds 314, 316,318, 320.

The slit valve plates/end pieces 302, 304 are each forged from a unitaryblock of material. As shown in FIG. 3B, the end pieces are carved back adistance shown by arrows “E” and have a rounded corner 322 that at leastpartially bounds the processing area. Due to the carving out of the slitvalve plates/end pieces 302, 304, the side pieces 310, 312 are bonded tothe slit valve plates/end pieces 302, 304 at locations spaced from thecorners 322. In one embodiment, the slit valve plates/end pieces 302,304 may be carved back about one half inch to about one inch.

Due to the large size of the processing area, portions of the load lockchamber may deflect when a vacuum is drawn in the processing area andwhen the processing area is vented to atmosphere. The corner 322 willtherefore be under the greatest stress as the corners are likely to feeltension from multiple directions. By spacing the location where the sidepieces 310, 312 are bonded to the slit valve plates/end pieces 302, 304,the bonding area or welds 314, 316, 318, 320 may be less likely to fail.The welds 314, 316, 318, 320, due to the fact that the welds 314, 316,318, 320, the side pieces 310, 312, and slit valve plates/end pieces302, 304 are not collectively a unitary piece of material, would beexpected to be the weakest point in the body 300. Thus, moving theweakest point to a location spaced from the greatest stress isbeneficial.

The welds 314, 316, 318, 320 may be formed by electron beam welding. Arcwelding like TIG or MIG may not be suitable for the thick material thatis used for large vacuum chambers. Electron beam welding has a higherenergy density than arc welding and enables the welding speed to befaster and deeper with a minimum amount of distortion. A smalldistortion in electron beams welding enables more rough machining of theslit valve plates/end pieces 302, 304 and side pieces 310, 312 prior towelding. The rough machining, as opposed to finely polished surfaces,reduces machining costs because each slit valve plate/piece 302, 304,310, 312 is small enough to be machined using a less expensive smallmachining center as opposed to a large machining facility for making thebody 300 out of a unitary material.

In one embodiment, the slit valve plates/end pieces 302, 304 and theside pieces 310, 312 may comprise the same material. In anotherembodiment, the slit valve plates/end pieces 302, 304 and the sidepieces 310, 312 may comprise different material. In one embodiment, thematerial may comprise aluminum. In another embodiment, the material maycomprise anodized aluminum. In another embodiment, the material maycomprise stainless steel.

FIG. 4 is an isometric view of the bonding location for a load lockchamber according to one embodiment. The end piece 402 is bonded to theside piece 404 by a weld 406 formed by e-beam welding. The end piece 402is forged from a piece of material and carved such that the corner 408that at least partially bounds the processing area has a curved surface.The welding location is disposed greater than about one eighth of aninch from the end of the radius of curvature. By spacing the weld 406from the corner 408, the stress concentration at the welding area isreduced. Additionally, the depth of the welding is decreased. The endpiece 402 is shown to have a greater width as shown by arrows “F” thanthe width of the side piece 404 as shown by arrows “G”. Because the weld406 is spaced form the corner 408, the side piece 404 may be made asthin as structurally possible.

FIG. 5A is an isometric view of two pieces to be welded together to forma portion of the load lock chamber body. The end piece 502 is initiallyspaced from the side piece 504 by a distance shown by arrows “J”. In oneembodiment, the distance “J” may be between about one quarter of an inchto about one half inch. The side piece 504 may be welded to the endpiece 502 by electron beam welding. The electron beam may be focusedinto the gap between the end piece 502 and side piece 504 as shown byarrows “H” at the bottom of the gap and move upwards as shown by arrows“I”. As shown in FIG. 5A, the electron beam is focused onto into the gapfrom outside of the processing area.

FIG. 5B is an isometric view of FIG. 5A after the two pieces have beenwelded together. FIG. 5C is an isometric view of FIG. 5B from adifferent angle. As can be seen from FIG. 5B, the outside surfaces ofside piece 504 and end piece 502 have a roughened weld 506 at the edges508, 510 due to the focusing of the electron beam from the outsidesurface. The other surfaces from which the electron beam was not focusedare much smoother and cleaner as shown by the edges 512, 514 on theinside surfaces of the end piece 502 and edge piece 504.

Generation 10 chambers are sized to accommodate substrates that are 2880mm by 3130 mm, which is quite large. The fabrication processes performedin chambers so large is difficult and pricy. Additionally, fabricatingthe chambers is difficult. To increase throughput, the load lockchambers may be used to cool down the substrate from temperatures ofbetween about 250 degrees Celsius to about 300 degrees Celsius down to atemperature of between about 100 degrees Celsius to about 150 degreesCelsius while the load lock is vented for a period of between about 45seconds to about 75 seconds so that the robot on the atmospheric side ofthe load lock chamber can remove the substrate from the load lockchamber.

The conduction/convection of the venting gas itself, such as nitrogen orargon, may not be sufficient to cool down the substrate to theappropriate temperature due to the high thermal mass and heat transferby radiation. In other words, the emissivity of the surfaces of the loadlock chamber may be a factor in cooling the substrate. To deal with theemissivity issues, the surfaces may be anodized, painted or beadblasted. Most anodizing, bead blasting or painting facilities are notlarge enough to accommodate a chamber as large as Generation 10 chamber.Therefore, the high emissivity coating disclosed herein is an attractiveoption.

Vacuum coating technology may be used to absorb a specific wavelength oflight. In one embodiment, the coating may comprise aluminum. The highemissivity coating permits the surface area of the chamber to increaseby 2000 times as compared to an uncoated surface and controls theemissivity at a wide range of the wavelength of light. The coating maybe done on the small parts of the chamber directly or applied byunrolling an aluminum foil that has a pressure sensitive adhesive on thesurface that will contact the chamber. The roll may be coated onto thesurface of the chamber on site without the need for surface treatmentssuch as anodization, bead blasting or painting and thus may be performedwithout additional logistical costs. The overall cost may be reduced by⅓ compared to anodization. Applying an aluminum coating is alsoecologically clean and toxic waste free.

The high emissivity coating may contribute to reducing the cool downtimes by permitting the substrate to cool from a temperature of betweenabout 250 degrees Celsius to about 300 degrees Celsius down to atemperature of between about 100 degrees Celsius to about 150 degreesCelsius in a time of between about 45 seconds to about 75 seconds. Inone embodiment, the high emissivity coating may have an emissivity ofbetween about 0.7 to about 0.9. The high emissivity coating may have athickness of between about 0.3 micrometers to about 14 micrometers. Inanother embodiment, the high emissivity coating may have a thickness ofbetween about 5 micrometers to about 7 micrometers. In anotherembodiment, the high emissivity coating may have a thickness of betweenabout 5 micrometers to about 7 micrometers. In another embodiment, thehigh emissivity coating may have a thickness of between about 7micrometers to about 14 micrometers. In another embodiment, the highemissivity coating may have a thickness of between about 6 micrometersto about 14 micrometers. In one embodiment, the high emissivity coatingmay comprise multiple layers. Suitable high emissivity coating may bepurchased from Acktar Advanced Coatings, LTD, Israel.

The high emissivity coating may be applied by simply unrolling thecoating material from a spool and pressing the coating onto the surfaceto be coated such that the adhesive side of the coating adheres to thesurface to be coated. In one embodiment, the high emissivity coating maybe between about 18 cm wide to about 22 cm wide and between about 3.1meters and about 3.3 meters in length. The high emissivity coating maybe applied on all exposed surfaces of the chamber if desired so long asthe coating does not interfere with the operations of the chamber.

FIG. 6 is a schematic top view of a coated chamber surface according toone embodiment. The plate 600 shown in FIG. 6 could be the top plate orthe bottom plate of an environment in the load lock chamber or anysurface of a load lock chamber, including a triple slot load lockchamber as shown in FIG. 1. The top plate and the bottom plate each havethe largest exposed surface areas of the elements that bound theprocessing area. The side pieces and end pieces are each smaller thanthe top plate and end plate. Additionally, the end plates have openingstherethrough sized to permit a substrate to enter and exit theprocessing area. The side pieces have openings therethrough to permit avacuum to be drawn in the processing area. Additionally, openings in theside pieces may permit metrology to be performed within the chamber orto introduce gas into the chamber.

In one embodiment, the body of the load lock chamber may comprisealuminum. In another embodiment, the body of the load lock chamber maycomprise anodized aluminum. Both aluminum and anodized aluminum arehighly reflective and have low emissivity. Aluminum has an emissivitycoefficient of 0.02 at 25 degrees Celsius, 0.03 at 100 degrees Celsius,and 0.06 at 500 degrees Celsius. Anodized aluminum, on the other hand,has an emissivity coefficient of 0.11 at 199 degrees Celsius and 0.19 at599 degrees Celsius. Aluminum is one of the most widely used materialsfor reflectance. Aluminum has a reflectance, on average, of greater thanabout 90 percent. Anodized aluminum does not reflect as much asaluminum, but the reflectance is still greater than 50 percent.

Substrates, when entering the load lock chamber from the transferchamber, may be at a temperature elevated above the temperature of thefactory interface. Thus, the load lock chamber may be used to lower thesubstrate temperature. With a highly reflective surface, the amount ofheat transfer from the substrate may not be very good. A high emissivitycoating 602 may be deposited onto the exposed surfaces of the plate 600.The high emissivity coating 602 may have a reflectance of less thanabout 4 percent and an emissivity coefficient of greater than about0.19. Thus, the high emissivity coating 602 may aid in heat transfer.The high emissivity coating 602 may be sufficient to be exposed tovacuum conditions without interfering or contaminating the substratesthat pass through the load lock chamber. The high emissivity coating 602may be continuous or may be spaced by gaps 604. The high emissivitycoating 602 may extend for substantially the entire width, shown byarrows “K” of the plate 600 and the width as shown by arrows “L”.

FIG. 7 is an isometric view of a coated chamber surface such as a plate700 according to another embodiment. As shown in FIG. 7, substratesupports 702 may span across the coating 704 perpendicular to the stripsof coating 704. The substrate supports 702 may have one or moresubstrate support pins 706 extending vertically therefrom to support asubstrate within the load lock chamber. The substrate is brought intothe chamber by a robot having an end effector. The end effector fitsbetween the substrate supports 702 and then lowers until the substraterests on the substrate support pins 706.

It is to be understood that while the embodiments disclosed herein havereferenced a load lock chamber for welding and for the high emissivitycoating, the welding and the high emissivity coating may be used inother chambers such as transfer chambers and processing chambers.Additionally, the welding may be used to fabricate a chamber even if thechamber is not lined with a high emissivity coating. Similarly, thechamber may be lined with a high emissivity coating even if the chamberis not fabricated by the welding technique disclosed herein. In oneembodiment, the chamber includes both a high emissivity coating as wellas the welded concept disclosed herein.

By coating one or more surfaces within a chamber with a high emissivitycoating, heat transfer from the substrate may occur at a faster rate acompared to an exposed, bare aluminum or anodized aluminum surface.Additionally, the electron beam welding separate pieces together at alocation spaced from the corner, the body of the chamber may be formedin a more cost effective manner so that larger forging equipment is notnecessary.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

The invention claimed is:
 1. A chamber body comprising a plurality ofpieces coupled together to collectively form the chamber body having aninside surface with four corners, the chamber body comprising: a firstpiece comprising: a first portion having a first length greater than afirst width and a first opening extending therethrough; a first flangeextending a first distance from the first portion in a directionsubstantially perpendicular to the first width, the first flangeextending from a first corner of the four corners; and a second flangeextending a second distance from the first portion in a directionsubstantially perpendicular to the first width, the second flangeextending from a second corner of the four corners; a second piececoupled to the first flange and extending in a direction substantiallyperpendicular to the first width; a third piece coupled to the secondflange and extending in a direction substantially perpendicular to thefirst width and parallel to the second piece; a fourth piece coupled tothe second piece and the third piece, the fourth piece comprising: asecond portion having a second length greater than a second width and asecond opening extending therethrough; a third flange extending a thirddistance from the second potion in a direction substantiallyperpendicular to the second width; and a fourth flange extending afourth distance from the second portion in a direction substantiallyperpendicular to the second width; a first plate coupled to the firstpiece, the second piece, the third piece and the fourth piece; a secondplate coupled to the first piece, the second piece, the third piece andthe fourth piece such that the first plate, the second plate, the firstpiece, the second piece, the third piece and the fourth piececollectively enclose a chamber volume; and a coating disposed on atleast one of the first plate and the second plate, the coating having anemissivity that is greater than the emissivity of at least one of thefirst piece, the second piece, the third piece and the fourth piece. 2.The chamber body of claim 1, wherein the first flange has a width thatis less than the first width, and the width of the first flange issubstantially equal to a width of the second piece.
 3. The chamber bodyof claim 2, wherein at least one corner of the four corners is rounded.4. The chamber body of claim 3, wherein the coating has an emissivity ofgreater than 0.19 measured at 599 degrees Celsius and a reflectance ofless than about 4 percent.
 5. The chamber body of claim 4, wherein thecoating comprises aluminum.
 6. A chamber, comprising: a top plate; abottom plate disposed opposite the top plate; a first side plate coupledto the top plate and the bottom plate; a second side plate coupled tothe top plate and the bottom plate and disposed opposite to the firstside plate; a first slit valve plate coupled to the top plate, thebottom plate, the first side plate and the second side plate and havingan opening therethrough; a second slit valve plate coupled to the topplate, the bottom plate, the first side plate and the second side plate,the second slit valve plate disposed opposite the first slit valve plateand having an opening therethrough, the top plate, the bottom plate, thefirst and second side plates, and the first and second slit valve platescollectively enclose a chamber volume; and a coating disposed on atleast one of the top plate and bottom plate, the coating having a firstemissivity that is greater than 0.19 measured at 599 degrees Celsius. 7.The chamber of claim 6, wherein the first emissivity is different thanthe emissivity of at least one of the first side plate, the second sideplate, the first slit valve plate and the second slit valve plate. 8.The chamber of claim 7, wherein the bottom plate has a coating thereonwith an emissivity greater than 0.19 measured at 599 degrees Celsius. 9.The chamber of claim 8, wherein the coating on the bottom plate is noncontinuous such that one or more gaps are present.
 10. The chamber ofclaim 9, further comprising one or more substrate supports coupled tothe bottom plate and extending along the bottom plate substantiallyperpendicular to the one or more gaps.
 11. The chamber of claim 10,further comprising one or more support pins coupled to and extendingvertically from the one or more substrate supports.
 12. The chamber ofclaim 11, wherein the coating has a reflectance of less than about 4percent.
 13. The chamber of claim 12, wherein the first slit valve platecomprises: a first portion having a first length greater than a firstwidth and a first opening extending therethrough; a first flangeextending a first distance from the first portion in a directionsubstantially perpendicular to the first width, the first flangeextending from a first corner of the four corners; and a second flangeextending a second distance from the first portion in a directionsubstantially perpendicular to the first width, the second flangeextending from a second corner of the four corners; wherein the secondslit valve plate comprises: a second portion a second length greaterthan a second width and a second opening extending therethrough; a thirdflange extending a third distance from the second potion in a directionsubstantially perpendicular to the second width; and a fourth flangeextending a fourth distance from the second portion in a directionsubstantially perpendicular to the second width; and wherein the firstside plate is coupled to the first flange and extends in a directionsubstantially perpendicular to the first width and wherein the secondside plate is coupled to the second flange and extending in a directionsubstantially perpendicular to the first width and parallel to thesecond piece.
 14. The chamber of claim 13, wherein the first flange hasa width that is less than the first width, and the width of the firstflange is substantially equal to a width of the second side plate. 15.The chamber of claim 14, wherein at least one corner of the four cornersis rounded.